Report on Rabaul (Papua New Guinea) — 21 February-27 February 2007
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 February-27 February 2007
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2007. Report on Rabaul (Papua New Guinea). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 February-27 February 2007. Smithsonian Institution and US Geological Survey.
Papua New Guinea
4.271°S, 152.203°E; summit elev. 688 m
All times are local (unless otherwise noted)
RVO reported that during 16-24 February, Rabaul caldera's Tavurvur cone emitted white vapor plumes that rose to 0.9-3.7 km (3,000-12,000 ft) a.s.l. and drifted N, W, and E. Ash clouds were emitted on 16, 19, 21, and 23-24 February and ashfall was reported from surrounding villages on 20 February. Loud roaring noises were occasionally heard. On 22 February, a moderate explosion produced fragments that showered the flanks. On 27 February, the Darwin VAAC reported that a diffuse plume was visible on satellite imagery. On 28 February, RVO reported a large explosion produced an ash plume that rose to an altitude of 2.7 km (8,900 ft) a.s.l. and drifted NE.
Geologic Background. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor utilized by what was the island's largest city prior to a major eruption in 1994. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the east, where its floor is flooded by Blanche Bay and was formed about 1400 years ago. An earlier caldera-forming eruption about 7100 years ago is now considered to have originated from Tavui caldera, offshore to the north. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city.
Sources: Darwin Volcanic Ash Advisory Centre (VAAC), Rabaul Volcano Observatory (RVO)